Difficulty staying connected to home network!

Hi,

I recently got a new internet provider in my home. I switched from AT@T to a local provider called Sonic. Since switching over I have had difficulty connecting to the network. It has to be a problem with my computer because I could connect with ease to my previous network, and the other people in my house are able to connect with the new network provider. Furthermore, when I check what wireless connections are available it shows my home network as really strong, but I can't connect to it!

My computer is only able to connect sometimes, and when my computer falls asleep and I turn it on again I can't connect. I have already done a few things I researched on the internet that may help such as deleting the network and adding it again. I have changed antennae diversity to Auxillary, I have disabled minimum power consumption. These did not really seem to change much. Still only intermittently able to be connected to my internet.

My computer: a DELL Inspiron 640m, and windows xp. I have a Dell Wireless 1390 WLAN Mini-Card.

Any help would be greatly appreciated! Thank you!